Control channel design for category-A devices

ABSTRACT

A user equipment device (UE) may communicate according to a new device category satisfying specified QoS (quality of service) requirements while also satisfying specified link budget requirements, and additional optimization requirements. The UE may use physical channels and procedures (e.g. it may receive and decode control channels) in a manner compatible with and not infringing on the operation of other UEs operating in the same network, while allowing the network more flexibility to assign resources. Specifically, resources for EPDCCH on UE-specific SS and EPDCCH on common SS may be shared. That is, the resources for two search spaces may be overlaid partially or in full, giving the network more flexibility in allocating resources. Furthermore the DCI formats for MPDCCH may be extended to devices operating according to the new device category, which enables the coverage enhancement of MTC for these devices.

PRIORITY CLAIM

This application claims benefit of priority of U.S. Provisional PatentApplication Ser. No. 62/339,726 titled “Control Channel Design forCategory A Devices”, filed on May 20, 2016, which is hereby incorporatedby reference as though fully and completely set forth herein.

FIELD OF THE INVENTION

The present application relates to wireless communications, and moreparticularly to control channel design for a new category of devices in3GPP wireless communications.

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage. In recentyears, wireless devices such as smart phones and tablet computers havebecome increasingly sophisticated. In addition to supporting telephonecalls, many mobile devices (i.e., user equipment devices or UEs) nowprovide access to the internet, email, text messaging, and navigationusing the global positioning system (GPS), and are capable of operatingsophisticated applications that utilize these functionalities.Additionally, there exist numerous different wireless communicationtechnologies and standards. Some examples of wireless communicationstandards include GSM, UMTS (WCDMA, TDS-CDMA), LTE, LTE Advanced(LTE-A), HSPA, 3GPP2 CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), IEEE802.11 (WLAN or Wi-Fi), IEEE 802.16 (WiMAX), BLUETOOTH™, etc.

Various ones of the wireless communications standards, such as LTE,utilize packet switched networks. The LTE specification defines a numberof User Equipment (UE) categories, where each LTE category defines theoverall performance and the capabilities of a UE. These LIE categoriesdefine the standards to which a particular handset, dongle or otherequipment will operate in the communication system. The LIE categoriesor UE classes are used to ensure that the base station (eNodeB or eNB)can communicate correctly with the user equipment. The UE relays the LIELE category information to the base station, and thus the base stationis able to determine the performance characteristics of the UE andcommunicate with the UE accordingly. This enables the eNB to communicateusing capabilities that it knows the UE possesses. While users may notbe particularly aware of the category of their LE, the performance ofthe LE matches the UE's category and allows the eNB to communicateeffectively with all the UEs that are connected to it. The LIE UPcategory information therefore may be important to the performance ofthe UE.

The eNB may be less likely to communicate beyond the performance of theUE corresponding to the category of the UR Thus it may be desirable tointroduce one or more new UE categories to provide for flexibility inoperation. U.S. Patent Application No. 62/274,353 titled “New DeviceCategory in 3GPP Communications” describes one possible category. It mayalso be desirable to provide an improved design for usage of controlchannels for the operation of wireless communication device devicesbelonging to any particular device category, especially a new devicecategory, e.g. the category disclosed in the above referenced U.S.patent application. Accordingly, improvements in the field aredesirable.

Other corresponding issues related to the prior art will become apparentto one skilled in the art after comparing such prior art with thedisclosed embodiments as described herein.

SUMMARY OF THE INVENTION

Embodiments are presented herein of, inter alia, methods for wirelesscommunication devices communicating, e.g. with cellular base stations,according to a new device category, and of devices that implement themethods. Embodiments are further presented herein for wirelesscommunication systems containing user equipment (UE) devices and basestations communicating with each other within the wireless communicationsystems.

In various embodiments, a UE may communicate according to a new devicecategory satisfying specified QoS (Quality of Service) requirementswhile also satisfying specified link budget requirements, and, in someembodiments, additional optimization requirements. The UE maycommunicate with a cellular base station according to the new devicecategory, and may switch to communicating with the cellular base stationin a way that the UE uses physical channels and/or procedures that arespecific to one or more other, different device categories. For example,the UE may switch to using physical channels and/or proceduresassociated with a second (pre-existing) device category if the linkbudget requirements exceed a specified value and the QoS requirementsare not sensitive, while communicating with the cellular base station.The UE may also switch to using physical channels and/or proceduresassociated with a third (pre-existing) device type if either the linkbudget requirement does not exceed the specified value, or the QoSrequirements are sensitive and a downlink throughput requirement exceedsa specified throughput value, while communicating with the cellular basestation.

Furthermore, a UE communicating according to the new device category mayuse physical channels and procedures (e.g. may receive and decodecontrol channels) in a manner compatible with and not infringing on theoperation of other UEs operating in the same network while allowing thenetwork more flexibility to assign resources. Specifically, resourcesfor EPDCCH (Enhanced Physical Downlink Control Channel) on UE-specificSS (Search Space) and EPDCCH on common SS may be optionally shared. Thatis, the resources for two search spaces may be overlaid partially or infull, giving the network more flexibility in allocating resources.Furthermore the DCI (Downlink Control Information) formats for MPDCCH(Machine Type Communications Physical Downlink Control Channel) may beextended to Cat-A devices, which enables the coverage enhancement of MTC(Machine Type Communications) for Cat-A devices. Specifically, at leastsome resources may be shared between the MPDCCH and the EPDCCH on commonSS for distributed transmissions, and/or some of the resources may beshared between the EPDCCH on common SS and EPDCCH on UE-specific SS,with resource elements transmitted on different ports in both cases inorder to allow resource sharing by multi-user MIMO methods. This allowsthe network to manage the resource sharing in a manner that istransparent to the UEs, although the UEs may advantageously usemulti-user MIMO methods in order to aid reception.

Pursuant to the above, a UE may perform wireless communications with acellular base station as device that identified to the cellular basestation as belonging to a first device category. According to variousembodiments disclosed herein, the first device category may be a newlydesignated and defined device category, herein name as Category A, orCat-A. The UE may thereby operate according to a plurality ofcommunication parameters that specify how the UE communicates with thecellular base station, and the UE may decode Downlink ControlInformation (DCI) on any physical channel from among: physical downlinkcontrol channel (PDCCH), enhanced PDCCH (EPDCCH) and/or Machine TypeCommunications PDCCH (MPDCCH). When decoding the DCI on the MPDCCH, theUE may recognize which DCI of multiple DCIs on the MPDCCH to decodebased at least on the length of the DCI.

In various embodiments, the length of the DCI (on the MPDCCH) decoded bythe UE is different from the length of other DCIs (on the MPDCCH) thatare decoded by other devices that belong to a different device categorythan the UE. That is, the difference between the length of the DCIdecoded by the UE on the MPDCCH and the length of the DCI decoded on theMPDCCH by the other devices allows respective receivers in the UE andthe other devices to recognize which DCI to decode.

For distributed transmissions, at least some resources may be sharedbetween the MPDCCH and the EPDCCH on common search space, and/or betweenthe EPDCCH on common search space and the EPDCCH on UE-specific searchspace. At least some of the resources may be shared by overlaying one ormore but not all physical resource block pairs. The resource elementsmay be transmitted on multiple respective ports, and the UE may accessthe shared resources through multi-user multiple-input-multiple-output(MIMO) methods. The sharing of the resources may be managed by thecellular base station and may remain transparent to the UE.

Note that the techniques described herein may be implemented in and/orused with a number of different types of devices, including but notlimited to, base stations, access points, cellular phones, portablemedia players, tablet computers, wearable devices, and various othercomputing devices.

This Summary is intended to provide a brief overview of some of thesubject matter described in this document. Accordingly, it will beappreciated that the above-described features are merely examples andshould not be construed to narrow the scope or spirit of the subjectmatter described herein in any way. Other features, aspects, andadvantages of the subject matter described herein will become apparentfrom the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary (and simplified) wireless communicationsystem, according to some embodiments;

FIG. 2 illustrates an exemplary base station in communication with anexemplary wireless user equipment (UE) device, according to someembodiments;

FIG. 3 illustrates an exemplary block diagram of a UE, according to someembodiments;

FIG. 4 illustrates an exemplary block diagram of a base station,according to some embodiments;

FIG. 5 shows an exemplary flow diagram illustrating communicationbetween a UE and a base station, according to some embodiments;

FIG. 6 shows a resource allocation diagram illustrating DMRS in anexemplary physical resource block pair when used for EPDCCH fordistributed transmission;

FIG. 7, shows a resource allocation diagram illustrating an exemplaryphysical resource block pair when used for EPDCCH for distributedtransmission on UE-specific search space;

FIG. 8 shows a resource allocation diagram illustrating an exemplaryphysical resource block pair when used for EPDCCH for distributedtransmission with some resource blocks allocated for common search spaceoverlaid with a UE-specific search space, according to some embodiments;

FIG. 9 shows a diagram illustrating how receive antennas may be used forreceiving physical control channel information, according to someembodiments;

FIG. 10 shows a resource allocation diagram illustrating DMRS in anexemplary physical resource block pair when used for EPDCCH forlocalized transmission;

FIG. 11 shows a resource allocation diagram illustrating an exemplaryphysical resource block pair when used for EPDCCH for localizedtransmission on UE-specific search space;

FIG. 12 shows a resource allocation diagram illustrating an exemplaryphysical resource block pair when used for EPDCCH for localizedtransmission with some resource blocks allocated for common search spaceoverlaid with a UE-specific search space, according to some embodiments;and

FIG. 13 shows an exemplary flow diagram illustrating wireless cellularcommunications of a UE, according to some embodiments.

While features described herein are susceptible to various modificationsand alternative forms, specific embodiments thereof are shown by way ofexample in the drawings and are herein described in detail. It should beunderstood, however, that the drawings and detailed description theretoare not intended to be limiting to the particular form disclosed, but onthe contrary, the intention is to cover all modifications, equivalentsand alternatives falling within the spirit and scope of the subjectmatter as defined by the appended claims.

DETAILED DESCRIPTION OF THE EMBODIMENTS Acronyms

Various acronyms are used throughout the present application.Definitions of the most prominently used acronyms that may appearthroughout the present application are provided below:

-   -   AP: Access Point    -   APR: Applications Processor    -   BS: Base Station    -   BSR: Buffer Size Report    -   BW: Bandwidth    -   CCE: Control Channel Element    -   CDM: Code Division Multiplexing    -   CMR: Change Mode Request    -   DL: Downlink (from BS to UE)    -   DMRS: Demodulation Reference Signal    -   ECCE: Enhanced Control Channel Element    -   EPDCCH: Enhanced Physical Downlink Control Channel    -   EREG: Enhanced Resource Element Group    -   FDD: Frequency Division Duplexing    -   FEC: Forward Error Correction Coding    -   GPRS: General Packet Radio Service    -   GSM: Global System for Mobile Communication    -   LAN: Local Area Network    -   LTE: Long Term Evolution    -   MPDCCH: MTC Physical Downlink Control Channel    -   OFDM: Orthogonal Frequency Division Multiplexing    -   PDCCH: Physical Downlink Control Channel    -   PDCP: Packet Data Convergence Protocol    -   PDN: Packet Data Network    -   PDSCH: Physical Downlink Shared Channel    -   PDU: Protocol Data Unit    -   PRB: Physical Resource Block    -   PUCCH: Physical Uplink Control Channel    -   QCI: Quality of Service Class Identifier    -   QoS: Quality of Service    -   RAR: Random Access Response    -   RAT: Radio Access Technology    -   RB: Resource Block    -   RE: Resource Element    -   RF: Radio Frequency    -   RNTI: Radio Network Temporary Identifier    -   RRC: Radio Resource Control    -   RTP: Real-time Transport Protocol    -   RX: Reception/Receive    -   SIB: System Information Block    -   SID: System Identification Number    -   SS: Search Space    -   TBS: Transport Block Size    -   TDD: Time Division Duplexing    -   TX: Transmission/Transmit    -   UE: User Equipment    -   UL: Uplink (from UE to BS)    -   UMTS: Universal Mobile Telecommunication System    -   Wi-Fi: Wireless Local Area Network (WLAN) RAT based on the        Institute of Electrical and Electronics Engineers' (IEEE) 802.11        standards    -   WLAN: Wireless LAN

Terms

The following is a glossary of terms that may appear in the presentapplication:

Memory Medium—Any of various types of memory devices or storage devices.The term “memory medium” is intended to include an installation medium,e.g., a CD-ROM, floppy disks 104, or tape device; a computer systemmemory or random access memory such as DRAM, DDR RAM, SRAM, EDO RAM,Rambus RAM, etc.; a non-volatile memory such as a Flash, magnetic media,e.g., a hard drive, or optical storage; registers, or other similartypes of memory elements, etc. The memory medium may comprise othertypes of memory as well or combinations thereof. In addition, the memorymedium may be located in a first computer system in which the programsare executed, or may be located in a second different computer systemwhich connects to the first computer system over a network, such as theInternet. In the latter instance, the second computer system may provideprogram instructions to the first computer system for execution. Theterm “memory medium” may include two or more memory mediums which mayreside in different locations, e.g., in different computer systems thatare connected over a network.

Carrier Medium—a memory medium as described above, as well as a physicaltransmission medium, such as a bus, network, and/or other physicaltransmission medium that conveys signals such as electrical,electromagnetic, or digital signals.

Computer System (or Computer)—any of various types of computing orprocessing systems, including a personal computer system (PC), mainframecomputer system, workstation, network appliance, Internet appliance,personal digital assistant (PDA), television system, grid computingsystem, or other device or combinations of devices. In general, the term“computer system” may be broadly defined to encompass any device (orcombination of devices) having at least one processor that executesinstructions from a memory medium.

User Equipment (UE) (or “UE Device”)—any of various types of computersystems devices which are mobile or portable and which performs wirelesscommunications. Also referred to as wireless communication devices.Examples of UEs include mobile telephones or smart phones (e.g.,iPhone™, Android™-based phones) and tablet computers such as iPad™,Samsung Galaxy™, etc., portable gaming devices (e.g., Nintendo DS™,PlayStation Portable™, Gameboy Advance™, iPod™), laptops, wearabledevices (e.g. Apple Watch™, Google Glass™), PDAs, portable Internetdevices, music players, data storage devices, or other handheld devices,etc. Various other types of devices would fall into this category ifthey include Wi-Fi or both cellular and Wi-Fi communication capabilitiesand/or other wireless communication capabilities, for example overshort-range radio access technologies (SRATs) such as BLUETOOTH™, etc.In general, the term “UE” or “UE device” may be broadly defined toencompass any electronic, computing, and/or telecommunications device(or combination of devices) which is easily transported by a user andcapable of wireless communication.

Base Station (BS)—The term “Base Station” has the full breadth of itsordinary meaning, and at least includes a wireless communication stationinstalled at a fixed location and used to communicate as part of awireless telephone system or radio system.

Processing Element—refers to various elements or combinations ofelements that are capable of performing a function in a device, e.g. ina user equipment device or in a cellular network device. Processingelements may include, for example: processors and associated memory,portions or circuits of individual processor cores, entire processorcores, processor arrays, circuits such as an ASIC (Application SpecificIntegrated Circuit), programmable hardware elements such as a fieldprogrammable gate array (FPGA), as well any of various combinations ofthe above.

Wireless Device (or wireless communication device)—any of various typesof computer systems devices which performs wireless communications usingWLAN communications, SRAT communications, Wi-Fi communications and thelike. As used herein, the term “wireless device” may refer to a UE, asdefined above, or to a stationary device, such as a stationary wirelessclient or a wireless base station. For example a wireless device may beany type of wireless station of an 802.11 system, such as an accesspoint (AP) or a client station (UE), or any type of wireless station ofa cellular communication system communicating according to a cellularradio access technology (e.g. LTE, CDMA, GSM), such as a base station ora cellular telephone, for example.

Wi-Fi—The term “Wi-Fi” has the full breadth of its ordinary meaning, andat least includes a wireless communication network or RAT that isserviced by wireless LAN (WLAN) access points and which providesconnectivity through these access points to the Internet. Most modernWi-Fi networks (or WLAN networks) are based on IEEE 802.11 standards andare marketed under the name “Wi-Fi”. A Wi-Fi (WLAN) network is differentfrom a cellular network.

BLUETOOTH™—The term “BLUETOOTH™” has the full breadth of its ordinarymeaning, and at least includes any of the various implementations of theBluetooth standard, including Bluetooth Low Energy (BTLE) and BluetoothLow Energy for Audio (BTLEA), including future implementations of theBluetooth standard, among others.

Personal Area Network—The term “Personal Area Network” has the fullbreadth of its ordinary meaning, and at least includes any of varioustypes of computer networks used for data transmission among devices suchas computers, phones, tablets and input/output devices. Bluetooth is oneexample of a personal area network. A PAN is an example of a short rangewireless communication technology.

Automatically—refers to an action or operation performed by a computersystem (e.g., software executed by the computer system) or device (e.g.,circuitry, programmable hardware elements, ASICs, etc.), without userinput directly specifying or performing the action or operation. Thusthe term “automatically” is in contrast to an operation being manuallyperformed or specified by the user, where the user provides input todirectly perform the operation. An automatic procedure may be initiatedby input provided by the user, but the subsequent actions that areperformed “automatically” are not specified by the user, i.e., are notperformed “manually”, where the user specifies each action to perform.For example, a user filling out an electronic form by selecting eachfield and providing input specifying information (e.g., by typinginformation, selecting check boxes, radio selections, etc.) is fillingout the form manually, even though the computer system must update theform in response to the user actions. The form may be automaticallyfilled out by the computer system where the computer system (e.g.,software executing on the computer system) analyzes the fields of theform and fills in the form without any user input specifying the answersto the fields. As indicated above, the user may invoke the automaticfilling of the form, but is not involved in the actual filling of theform (e.g., the user is not manually specifying answers to fields butrather they are being automatically completed). The presentspecification provides various examples of operations beingautomatically performed in response to actions the user has taken.

Station (STA)—The term “station” herein refers to any device that hasthe capability of communicating wirelessly, e.g. by using the 802.11protocol. A station may be a laptop, a desktop PC, PDA, access point orWi-Fi phone or any type of device similar to a UE. An STA may be fixed,mobile, portable or wearable. Generally in wireless networkingterminology, a station (STA) broadly encompasses any device withwireless communication capabilities, and the terms station (STA),wireless client (UE) and node (BS) are therefore often usedinterchangeably.

Configured to—Various components may be described as “configured to”perform a task or tasks. In such contexts, “configured to” is a broadrecitation generally meaning “having structure that” performs the taskor tasks during operation. As such, the component can be configured toperform the task even when the component is not currently performingthat task (e.g., a set of electrical conductors may be configured toelectrically connect a module to another module, even when the twomodules are not connected). In some contexts, “configured to” may be abroad recitation of structure generally meaning “having circuitry that”performs the task or tasks during operation. As such, the component canbe configured to perform the task even when the component is notcurrently on. In general, the circuitry that forms the structurecorresponding to “configured to” may include hardware circuits.

Various components may be described as performing a task or tasks, forconvenience in the description. Such descriptions should be interpretedas including the phrase “configured to.” Reciting a component that isconfigured to perform one or more tasks is expressly intended not toinvoke 35 U.S.C. § 112, paragraph six, interpretation for thatcomponent.

FIGS. 1 and 2—Exemplary Communication System

FIG. 1 illustrates an exemplary (and simplified) wireless communicationsystem, according to some embodiments. It is noted that the system ofFIG. 1 is merely one example of a possible system, and embodiments maybe implemented in any of various systems, as desired.

As shown in FIG. 1, the exemplary wireless communication system includesa base station 102 which communicates over a transmission medium withone or more user devices 106-1 through 106-N. Each of the user devicesmay be referred to herein as a “user equipment” (UE) or UE. Thus, theuser devices 106 are referred to as UEs or UE devices. Various ones ofthe UEs may operate according to a new category [definition] as detailedherein.

The base station 102 may be a base transceiver station (BTS) or cellsite, and may include hardware that enables wireless communication withthe UEs 106A through 106N. The base station 102 may also be equipped tocommunicate with a network 100 (e.g., a core network of a cellularservice provider, a telecommunication network such as a public switchedtelephone network (PSTN), and/or the Internet, among variouspossibilities). Thus, the base station 102 may facilitate communicationbetween the user devices and/or between the user devices and the network100. The communication area (or coverage area) of the base station maybe referred to as a “cell.” As also used herein, from the perspective ofUEs, a base station may sometimes be considered as representing thenetwork insofar as uplink and downlink communications of the UE areconcerned. Thus, a UE communicating with one or more base stations inthe network may also be interpreted as the UE communicating with thenetwork. It should also be noted that “cell” may also refer to a logicalidentity for a given coverage area at a given frequency. In general, anyindependent cellular wireless coverage area may be referred to as a“cell”. In such cases a base station may be situated at particularconfluences of three cells. The base station, in this uniform topology,may serve three 120-degree beam-width areas referenced as cells. Also,in case of carrier aggregation, small cells, relays, etc. may eachrepresent a cell. Thus, in carrier aggregation in particular, there maybe primary cells and secondary cells which may service at leastpartially overlapping coverage areas but on different respectivefrequencies. For example, a base station may serve any number of cells,and cells served by a base station may or may not be collocated (e.g.remote radio heads).

The base station 102 and the user devices may be configured tocommunicate over the transmission medium using any of various radioaccess technologies (RATs), also referred to as wireless communicationtechnologies, or telecommunication standards, such as GSM, UMTS (WCDMA),LTE, LTE-Advanced (LTE-A), 3GPP2 CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD,eHRPD), Wi-Fi, WiMAX etc. In some embodiments, the base station 102communicates with at least one UE using improved UL (Uplink) and DL(Downlink) decoupling, preferably through LTE or a similar RAT standard.

UE 106 may be capable of communicating using multiple wirelesscommunication standards. For example, a UE 106 might be configured tocommunicate using either or both of a 3GPP cellular communicationstandard (such as LTE) or a 3GPP2 cellular communication standard (suchas a cellular communication standard in the CDMA2000 family of cellularcommunication standards). In some embodiments, the UE 106 may beconfigured to communicate with base station 102 at least according to anew and improved category designation/definition of UE 106 as describedherein. Base station 102 and other similar base stations operatingaccording to the same or a different cellular communication standard maythus be provided as one or more networks of cells, which may providecontinuous or nearly continuous overlapping service to UE 106 andsimilar devices over a wide geographic area via one or more cellularcommunication standards.

The UE 106 might also or alternatively be configured to communicateusing WLAN, BLUETOOTH™, one or more global navigational satellitesystems (GNSS, e.g., GPS or GLONASS), one and/or more mobile televisionbroadcasting standards (e.g., ATSC-M/H or DVB-H), etc. Othercombinations of wireless communication standards (including more thantwo wireless communication standards) are also possible.

FIG. 2 illustrates an exemplary user equipment 106 (e.g., one of thedevices 106-1 through 106-N) in communication with the base station 102,according to some embodiments. The UE 106 may be a device with wirelessnetwork connectivity such as a mobile phone, a hand-held device, acomputer or a tablet, or virtually any type of wireless device. The UE106 may include a processor that is configured to execute programinstructions stored in memory. The UE 106 may perform any of the methodembodiments described herein by executing such stored instructions.Alternatively, or in addition, the UE 106 may include a programmablehardware element such as an FPGA (field-programmable gate array) that isconfigured to perform any of the method embodiments described herein, orany portion of any of the method embodiments described herein. The UE106 may be configured to communicate using any of multiple wirelesscommunication protocols. For example, the UE 106 may be configured tocommunicate using two or more of CDMA2000, LTE, LTE-A, WLAN, or GNSS.Other combinations of wireless communication standards are alsopossible.

The UE 106 may include one or more antennas for communicating using oneor more wireless communication protocols according to one or more RATstandards. In some embodiments, the UE 106 may share one or more partsof a receive chain and/or transmit chain between multiple wirelesscommunication standards. The shared radio may include a single antenna,or may include multiple antennas (e.g., for MIMO) for performingwireless communications. Alternatively, the UE 106 may include separatetransmit and/or receive chains (e.g., including separate antennas andother radio components) for each wireless communication protocol withwhich it is configured to communicate. As another alternative, the UE106 may include one or more radios which are shared between multiplewireless communication protocols, and one or more radios which are usedexclusively by a single wireless communication protocol. For example,the UE 106 may include a shared radio for communicating using either ofLTE or CDMA2000 1×RTT, and separate radios for communicating using eachof Wi-Fi and BLUETOOTH™. Other configurations are also possible.

FIG. 3—Block Diagram of an Exemplary UE

FIG. 3 illustrates a block diagram of an exemplary UE 106, according tosome embodiments. As shown, the UE 106 may include a system on chip(SOC) 300, which may include portions for various purposes. For example,as shown, the SOC 300 may include processor(s) 302 which may executeprogram instructions for the UE 106 and display circuitry 304 which mayperform graphics processing and provide display signals to the display360. The processor(s) 302 may also be coupled to memory management unit(MMU) 340, which may be configured to receive addresses from theprocessor(s) 302 and translate those addresses to locations in memory(e.g., memory 306, read only memory (ROM) 350, NAND flash memory 310)and/or to other circuits or devices, such as the display circuitry 304,radio 330 circuitry, connector I/F 320, and/or display 360. The MMU 340may be configured to perform memory protection and page tabletranslation or set up. In some embodiments, the MMU 340 may be includedas a portion of the processor(s) 302.

FIG. 3 illustrates a block diagram of an exemplary UE 106, according tosome embodiments. As shown, the UE 106 may include a system on chip(SOC) 300, which may include portions for various purposes. For example,as shown, the SOC 300 may include processor(s) 302 which may executeprogram instructions for the UE 106 and display circuitry 304 which mayperform graphics processing and provide display signals to the display360. The processor(s) 302 may also be coupled to memory management unit(MMU) 340, which may be configured to receive addresses from theprocessor(s) 302 and translate those addresses to locations in memory(e.g., memory 306, read only memory (ROM) 350, NAND flash memory 310)and/or to other circuits or devices, such as the display circuitry 304,radio circuitry 330, connector I/F 320, and/or display 360. The MMU 340may be configured to perform memory protection and page tabletranslation or set up. In some embodiments, the MMU 340 may be includedas a portion of the processor(s) 302.

As described further subsequently herein, the UE 106 (and/or basestation 102) may include hardware and software components forimplementing methods for UE 106 [and base station 102] communicating[with each other] at least according to a new and improved categorydesignation of UE 106, including decoding physical control channels aswill be further described herein. The processor(s) 302 of the UE 106 maybe configured to implement part or all of the methods described herein,e.g., by executing program instructions stored on a memory medium (e.g.,a non-transitory computer-readable memory medium). In other embodiments,processor(s) 302 may be configured as a programmable hardware element,such as an FPGA (Field Programmable Gate Array), or as an ASIC(Application Specific Integrated Circuit). Furthermore, processor(s) 302may be coupled to and/or may interoperate with other components as shownin FIG. 3, to implement communications by UE 106 that incorporatescommunications corresponding to a new, improved category designation ofUE 106, such communications including the decoding of physical controlchannels according to various embodiments disclosed herein. Processor(s)302 may also implement various other applications and/or end-userapplications running on UE 106.

In some embodiments, radio circuitry 330 may include separatecontrollers dedicated to controlling communications for variousrespective RAT standards. For example, as shown in FIG. 3, radiocircuitry 330 may include a Wi-Fi controller 350, a cellular controller352 (e.g. LTE controller), and BLUETOOTH™ controller 354, and in atleast some embodiments, one or more or all of these controllers may beimplemented as respective integrated circuits (ICs or chips, for short)in communication with each other and with SOC 300 (and more specificallywith processor(s) 302) as will be further described below. For example,Wi-Fi controller 350 may communicate with cellular controller 352 over acell-ISM link or WCI interface, and/or BLUETOOTH™ controller 354 maycommunicate with cellular controller 352 over a cell-ISM link, etc.While three separate controllers are illustrated within radio circuitry330, other embodiments have fewer or more similar controllers forvarious different RATs that may be implemented in UE 106.

FIG. 4—Block Diagram of an Exemplary Base Station

FIG. 4 illustrates a block diagram of an exemplary base station 102,according to some embodiments. It is noted that the base station of FIG.4 is merely one example of a possible base station. As shown, the basestation 102 may include processor(s) 404 which may execute programinstructions for the base station 102. The processor(s) 404 may also becoupled to memory management unit (MMU) 440, which may be configured toreceive addresses from the processor(s) 404 and translate thoseaddresses to locations in memory (e.g., memory 460 and read only memory(ROM) 450) or to other circuits or devices.

The base station 102 may include at least one network port 470. Thenetwork port 470 may be configured to couple to a telephone network andprovide a plurality of devices, such as UEs 106, access to the telephonenetwork as described above in FIGS. 1 and 2. The network port 470 (or anadditional network port) may also or alternatively be configured tocouple to a cellular network, e.g., a core network of a cellular serviceprovider. The core network may provide mobility related services and/orother services to a plurality of devices, such as UEs 106. In somecases, the network port 470 may couple to a telephone network via thecore network, and/or the core network may provide a telephone network(e.g., among other UEs serviced by the cellular service provider).

The base station 102 may include at least one antenna 434, and possiblymultiple antennas. The at least one antenna 434 may be configured tooperate as a wireless transceiver and may be further configured tocommunicate with UEs 106 via radio 430. The antenna 434 communicateswith the radio 430 via communication chain 432. Communication chain 432may be a receive chain, a transmit chain or both. The radio 430 may bedesigned to communicate via various wireless telecommunicationstandards, including, but not limited to, LTE, LTE-A WCDMA, CDMA2000,etc. The processor(s) 404 of the base station 102 may be configured toimplement part or all of the methods described herein for base station102 to communicate with a UE belonging to a new category of devicescapable of adaptively improving power consumption, link budgetmanagement, and performance during wireless communications, e.g., byexecuting program instructions stored on a memory medium (e.g., anon-transitory computer-readable memory medium). Alternatively, theprocessor(s) 404 may be configured as a programmable hardware element,such as an FPGA (Field Programmable Gate Array), or as an ASIC(Application Specific Integrated Circuit), or a combination thereof. Inthe case of certain RATs, for example Wi-Fi, base station 102 may bedesigned as an access point (AP), in which case network port 470 may beimplemented to provide access to a wide area network and/or local areanetwork (s), e.g. it may include at least one Ethernet port, and radio430 may be designed to communicate according to the Wi-Fi standard. Basestation 102 may operate according to the various methods as disclosedherein for communicating with mobile devices of a wider range of devicecategories.

Device Categories

There are many different device category definitions for LTE devices.For example, categories 1-8 are designated for smartphones, and mostphones operate according to one of categories 3 to 8. In other words,smartphones typically operate as a device belonging to one of categories3-8. Category M (Cat-M) is typically used for MTC (Machine TypeCommunications) devices such as soda machines, smart meters, etc. Insome embodiments, a new category A (Cat-A) may be devised and tailoredto a specific group of devices, for example to wearable devices such assmart watches or smart glasses or the like. In terms of functionality,wearable devices represent a compromise between link budget and qualityof service (QoS). Thus, when considering current existing categories, itmay be advantageous to retain the link budget improvement associatedwith Cat-M because of the form factor, while also retaining the QoS ofsmart phone categories for higher quality and more reliable wirelesscommunications. Typically, if a Cat-M device has to report itselectricity usage to the network, there is no need for the device totransmit such a report during peak wireless network traffic hours suchas between 9 AM and noon. Instead, the device may transmit the reportduring off-peak hours, e.g. 3 AM when there is little or no networktraffic. It may be considered difficult for the network to access thedevice in the middle of the day. Moreover, Cat-M does not necessarilysupport real-time applications. It would therefore be desirable todevise a new category satisfying QoS requirements along with an improvedlink budget (i.e. also satisfying certain link budget requirements), andpotentially implementing additional desired optimizations. U.S. PatentApplication No. 62/274,353 titled “New Device Category in 3GPPCommunications” describes one such possible category designated asCategory A, or Cat-A.

Cat-A DL Mode of Operation

Considering the new category (Cat-A), if the benefit of narrowband modeof operation is not sufficient or not needed, then in DL (downlink) modethe UE may operate according to a legacy Cat-1 mode of operation whileremaining identified as a Cat-A device. In other words, if there is noneed for a narrowband mode of operation in DL, then a Cat-A device maysimply operate according to certain features, e.g. certain channelsand/or mode of operation associated with a different device category,e.g. operate according to certain features and procedures associatedwith a legacy Cat-1 device during DL communications/operations. For linkbudget enhancement, CE (coverage enhancements) from a differentcategory, e.g. Cat-M, may be reused for operation if desired. Overall,Cat-M operation may be used for all the common channels whileUE-specific data may be handled according to Cat-A requirements (for aCat-A UE). Thus, a Cat-A device may also have modes of operationassociated with other device categories. In some embodiments, a Cat-Adevice may have Cat-1 and/or Cat-M modes of operation, which means thatthe Cat-A UE may use some PHY channels and/or procedures that arespecific to (associated with) those different categories. For example,Cat-1 mode of operation means use of PDCCH, and Cat-M mode of operationmeans use of MPDCCH and narrowband (1.4 MHz) operation. It should benoted that the modes of operation described above are also referred toherein as “operating according to a different device category”. Forexample, when a (Cat-A) UE is said to be operating according to Cat-1,it means that the Cat-A UE uses some channels and/or procedures that arespecific to Cat-1, while the UE remains identified as a Cat-A device.

UL communications may always take place in a narrowband mode ofoperation. For example, during UL operations, the UE may operate in atmost (i.e. maximum) a specified first bandwidth, e.g. 3 MHz bandwidth.During DL communications, the UE may operate in a second specifiedbandwidth, e.g. a 10 MHz bandwidth, independently of the systembandwidth, or the UE may operate in the system bandwidth. Furthermore,in some embodiments, a Cat-A device may always operate in asymmetricbandwidths for UL and DL operations. In other words, in someembodiments, a Cat-A device may operate in a specified first (or firstsize) bandwidth for DL operations and a specified second (or secondsize) bandwidth for UL operations, where the first bandwidth differsfrom the second bandwidth. It should be noted that in this context thebandwidth references the size of the bandwidth and not any specificfrequency range associated with the bandwidth. For example, a specifiedfirst bandwidth may be situated at any specified or designated region ofthe frequency spectrum per the specific RAT designation(s).

Consequently, if a narrowband mode of operation in DL is justified bythe architecture, then a Cat-A device may operate in a specified systemband for efficiency, e.g. in 10 MHz for energy efficiency (it should benoted that operating in a 1.4 MHz band has an impact on powerconsumption for heavy DL traffic). For link budget enhancement andcommon channels, a Cat-A UE may operate using features, channels and/orprocedures specific to a Cat-M device (i.e. operate in a 1.4 MHzbandwidth). In a way, during some time periods the UE may be said toswitch from operating as a Cat-A device to operating as a Cat-M device.However, as mentioned above, this doesn't mean that the UE changes itscategory designation or that the category designation of the UE isredefined/modified. In some embodiments, this change in mode ofoperation includes changing the mode of operation for the PHY channelsand the system bandwidth. For example, if link budget enhancements areneeded, the UE may operate in 1.4 MHz bandwidth and use the MPDCCH as aCat-M device would, but the UE still remains a Cat-A device.

Defining Cat-A in terms of Cat-1

In some embodiments, Cat-A may be defined in terms of Cat-1 withnarrowband operation in UL/DL. That is, a Cat-A device may be considereda Cat-1 device with a single receive (RX) antenna, and may reuse Cat-Magreements for common channels (RAR/Paging/SIB) and extensions ifneeded, and may further use of Cat-M mode (i.e. MPDCCH, time domainrepetitions and 1.4 MHz) in idle mode and during attach procedure. ForUL, if new RACH preambles are introduced in Cat-A, the PUCCH may differ,while in Cat-M, PUCCH is restricted to 1.4 MHz whereas Cat-A operatesaccording to legacy PUCCH.

As soon as RRC connection reconfiguration is complete, the UE may beoperating as a fully Cat-A device, i.e. it may use EPDCCH forUE-specific data, and operate in 10 MHz in DL mode, and in 3 MHz in ULmode. For a link budget improvement higher than 5 dB and QoSrequirements that are not sensitive, the UE may switch to a Cat-M modeof operation as previously described (in other words, the UE may remaina Cat-A device while using a mode of operation specific to or associatedwith Cat-M), i.e. operating in a 1.4 MHz band with time domainrepetitions. For a link budget improvement lower than 5 dB, the UE mayswitch to a Cat-1 mode of operation. For QCI1 (e.g. real-timeapplications, VoLTE or similar QoS, QoS that are sensitive for e.g.real-time applications)/Heavy DL throughput and regardless of the linkbudget improvement needed (i.e. be it more than 5 dB or less than 5 dB),the UE may again switch to a Cat-1 mode of operation.

The switch from operating according to a mode of operation associatedwith one category to operating according to a mode of operationassociated with another category may be performed at the eNB through RRCsignaling. The UE may be identified as a Cat-A device, but based on thelink budget, the QoS and/or the throughput/power consumptionrequirements, the eNB may enable the most appropriate (or mostadvantageous) mode of operation (e.g. PHY channels like MPDCCH, 1.4 MHzmode of operation, EPDCCH, common channels procedures, etc.) The switchmay be requested by the wireless communication device (e.g. in form ofMAC CE/RRC signaling) or it may be triggered by the NW based onmeasurements available at the NW (e.g. RSRP/CQI/PHR/BSR/BLER, etc.) Itshould also be noted that while there are at least three modes ofoperation of a Cat-A device disclosed herein, operation of Cat-A devicesis not restricted to the examples provided herein. For example, in someembodiments, when certain conditions are met a Cat-A device may operateaccording to procedures and/or use of channels associated with otherdevice categories not specifically mentioned herein, in addition toCat-1 and Cat-M modes of operation. Furthermore, a Cat-A device mayoperate according to the requirements specified for a Cat-A device atall times, while under certain conditions—as also previously disclosedherein—the device may switch between performing respective operationsaccording to corresponding procedures and/or use of channels associatedwith different categories.

FIG. 5 shows an exemplary flow diagram illustrating communicationsbetween a UE and a cellular base station according to some embodiments.The UE may be identified as belonging to a first device category, whichmay be a new device category (or type) such as Cat-A as disclosed above(502). The UE may communicate with a cellular base station according toa mode of operation associated with (or specific to) the first devicecategory (520). If the link budget requirement exceeds a specified value(504) and the QoS requirements are not sensitive, i.e. the QoSrequirements don't meet certain criteria (506), the UE may switch tocommunicating with the cellular base station according to a mode ofoperation associated with a second device category, e.g. associated witha pre-existing device category such as Cat-M in some embodiments (510).If the link budget requirement does not exceed the specified value(504), the UE may switch to communicating with the cellular base stationaccording to a mode of operation associated with a third devicecategory, e.g. associated with another pre-existing device category suchas Cat-1 in some embodiments (512). Furthermore, if the QoS requirementsare sensitive, i.e. they meet certain criteria, and/or downlinkthroughput requirements exceed a specified throughput value (508), theUE may switch to communicating with the cellular base station accordingto the mode of operation associated with the third device category(512).

Control Channels in LTE

LTE defines a number of downlink (DL) physical channels, categorized astransport or control channels, to carry information blocks received fromthe MAC and higher layers. LTE also defines three physical layerchannels for the uplink (UL).

The Physical Downlink Shared Channel (PDSCH) is a DL transport channel,and is the main data-bearing channel allocated to users on a dynamic andopportunistic basis. The PDSCH carries data in Transport Blocks (TB)corresponding to a media access control protocol data unit (MAC PDU),passed from the MAC layer to the physical (PHY) layer once perTransmission Time Interval (TTI). The PDSCH is also used to transmitbroadcast information such as System Information Blocks (SIB) and pagingmessages.

The Physical Downlink Control Channel (PDCCH) is a DL control channelthat carries the resource assignment for UEs that are contained in aDownlink Control Information or Indicator (DCI) message. Multiple PDCCHscan be transmitted in the same subframe using Control Channel Elements(CCE), each of which is a nine set of four resource elements known asResource Element Groups (REG). The PDCCH employs quadrature phase-shiftkeying (QPSK) modulation, with four QPSK symbols mapped to each REG.Furthermore, 1, 2, 4, or 8 CCEs can be used for a UE, depending onchannel conditions, to ensure sufficient robustness.

The Physical Uplink Shared Channel (PUSCH) is a UL channel shared by alldevices (user equipment, UE) in a radio cell to transmit user data tothe network. The scheduling for all UEs is under control of the LTE basestation (enhanced Node B, or eNB). The eNB uses the uplink schedulinggrant (DCI format 0) to inform the UE about resource block (RB)assignment, and the modulation and coding scheme to be used. PUSCHtypically supports QPSK and quadrature amplitude modulation (QAM).

The Physical Hybrid ARQ Indicator Channel (PHICH) is a DL controlchannel that carries the HARQ acknowledge/negative-acknowledge(ACK/NACK), indicating to the UE whether the eNB correctly receiveduplink user data carried on the PUSCH. Information over the PHICH istypically BPSK (binary phase shift keying) modulated.

The Physical Control Format Indicator Channel (PCFICH) is a DL controlchannel that carries the Control Frame Indicator (CFI) which includesthe number of orthogonal frequency-division multiplexing (OFDM) symbolsused for control channel transmission in each subframe (typically 1, 2,or 3). The 32-bit long CFI is mapped to 16 Resource Elements in thefirst OFDM symbol of each downlink frame using QPSK modulation.

Therefore, as indicated above, during data communication over LTE, theDL uses the physical channel PDSCH, while in UL it uses the UL channelPUSCH. As also mentioned above, these two channels convey the transportblocks of data in addition to some MAC control and system information.To support the transmission of DL and UL transport channels, DownlinkShared Channel (DLSCH) and Uplink Shared Channel (UL-SCH) controlsignaling is required. This control information is sent in PDCCH and itcontains DL resource assignment and UL grant information. PDCCH is sentin the beginning of every subframe in the first OFDM symbols. Dependingon the level of robustness and the PDCCH system capacity (numbers ofusers to be simultaneously served in a TTI) the NW needs to achieve,PDCCH will be transmitted in either the first 1, 2, 3, or 4 OFDM symbolsof a subframe. The number of OFDM symbols used in PDCCH is typicallysignaled in PCFICH.

Control Channel Considerations for Cat-A

One limitation during DL operations may be the control channel, PDCCH.EPDCCH is UE-specific and is used in RRC-connected mode and cannot beused for common channels like paging, SIB, etc. PDCCH may be replacedfor Cat-A devices according to at least two different solutions. In afirst solution, the EPDCCH may be extended to be used for idle mode andcommon channels, SIB/RAR/Paging. For RAR and Paging it may include adefinition of new reserved preambles for RACH, and a new UE_ID forpaging for this new category (Cat-A) devices.

In a second solution, the MPDCCH may be reused for RAR/Paging andMTC_SIB may be used (where MTC stands for machine-type communications),while EPDCCH may be used for UE-specific data. It should be noted thatMTC_SIB does not require a PDCCH. Consequently, RAR and Paging may beoperating in narrowband (e.g. 1.4 MHz) like a Cat-M device. Before RRCconnection reconfiguration is reached, MPDCCH may be used. Once RRCconnection reconfiguration has been reached, a complete switch to EPDCCHmay take place since EPDCCH in the specification is UE specific and usedonly in RRC connected mode. Thus, to use EPDCCH, a configuration isexpected from the network, and that configuration may be received in anRRC connection reconfiguration transmission.

Furthermore, MTC_SIB may be made to cover all legacy SIBs. Since an MTCdevice may not support mobility, SIB4/5 may most likely not be redefinedfor MTC. Hence for Cat-A, new SIBs 4/5/10/11/12 may be created. SIBs 4and 5 may be for mobility, SIBs 11 and 12 may be for emergency calls asthe new category supports emergency calls. Overall, the new SIBs may becreated to operate without PDCCH, i.e. they may operate without usingPDCCH as MTC_SIB. The PRB s pairs used for EPDCCH may be restricted tofit a specified bandwidth, which is 10 MHz in some embodiments. Prior toattaching to the NW, the UE may be operating using physical channelsand/or procedures associated with a different category mode, e.g. Cat-Mmode, while the UE may still be identified as a Cat-A device. In otherwords, the UE may not be identified as Cat-M device, but at the sametime the UE may use MPDCCH and common channels (SIB/RACH/Paging) asdefined for (associated with) Cat-M because MPDCCH and the abovereferenced common channels support a narrowband mode of operation (1.4MHz). An example code sequence corresponding to EPDCCH configuration isshown below:

EPDCCH-SetConfig-r11 ::= SEQUENCE { setConfigId-r11EPDCCH-SetConfigId-r11, transmissionType-r11 ENUMERATED {localised,distributed}, resourceBlockAssignment-r11 SEQUENCE{ numberPRB-Pairs-r11ENUMERATED {n2, n4, n8}, resourceBlockAssignment-r11 BIT STRING(SIZE(4..38)) // This may be restricted to fit in 10 MHz },Expanded Cat-A Control Channel Operations

As mentioned above, in the 3GPP LTE standard, the Physical DownlinkControl Channel (PDCCH) is used as the control channel and istransmitted over the entire bandwidth in the first few OFDM symbols of asubframe. A subframe generally comprises 14 OFDM symbols (normal cyclicprefix) of which one to four symbols can be used for PDCCH. Anadditional control channel—also defined in 3GPP—and transmitted in thePDSCH portion of a subframe is called an Enhanced PDCCH or EPDCCH. TheEPDCCH may be assigned to UE's once they are in the network, and mayonly be assigned to a UE in an RRC-connected state. Thus the EPDCCHassigned to a UE can carry control channels directed to a specific UE,which is referred to as UE-specific search-space (SS). In other words,once the UE is in a connected state the network might assign the UEcertain resources. However, these resources are not exclusively assignedand may be reused by the network for regular PDSCH. The EPDCCHs may bedecoded blindly by the UE on the assigned EPDCCH resources according tothe specified procedures to match with its C-RNTI (Cell Radio NetworkTemporary Identifier) in a DCI.

In some embodiments, the idea of EPDCCH is extended to a common SS asdescribed in U.S. patent application Ser. No. 15/076,967, which makespaging Downlink Control Information (DCIs with Paging RNTI, or P-RNTI)on EPDCCH possible. The common SS may also be used for systeminformation messages (with System Information RNTI, or SI-RNTI).Extending EPDCCH in this manner is useful at least because Cat-A devicesmay be limited in bandwidth (BW). E.g. while a cell BW may be 20 MHz, aCat-A device might be operating with a 10 MHz BW. In that case the Cat-Adevice may not be able to decode PDCCH anymore, and may need to rely onEPDCCH.

3GPP Release 13 also defines a control channel for MTC class of devicesor Cat-M devices, labelled MPDCCH. MPDCCH is similar to EPDCCH, but theBW of MTC class devices is limited to 6 RBs, and there are also specialDCIs defined for MTC class devices. As mentioned above, a new categorydevice, specifically named Cat-A device may be defined with somespecific needs. The Cat-A devices may potentially decode all differentcontrol channels: PDCCH, EPDCCH on UE-specific SS, EPDCCH on common SS,and MPDCCH.

Thus, further extensions to the control channel structure(s) may beimplemented to service Cat-A devices. Specifically, the concept ofEPDCCH may be extended to common SS, and some of the resources forEPDCCH on UE-specific SS, and EPDCCH on common SS may be optionallyshared. In other words, the resources for two search spaces may beoverlaid partially or in full, giving the network more flexibility inallocating resources. Furthermore the DCI formats for MPDCCH may beextended to Cat-A devices, which enables the coverage enhancement of MTCfor Cat-A devices. Because Cat-A devices can use up to fifteen (15)resource blocks (RBs) whereas MTC devices are limited to 6 RBs, new DCIformats enable Cat-A devices to operate/function properly when usingMPDCCH.

EPDCCH

Per 3GPP LTE specs, EPDCCH assignments are made for UE-specific searchspace. The assignment of EPDCCH to a UE is made after the RRC connectionwith the UE has been established. The EPDCCH is therefore not used forUEs that are in RRC-Idle state. Two sets of up to eight (8) RBs may beallocated for EPDCCH for a UE. Each RB may carry four (4) ECCEs. TheEPDCCH thereby allows higher aggregation levels (L=16, 32) compared toPDCCH (L=8). It should be noted however that for normal subframes anECCE includes 4 EREGs but an EREG does not always contain nine (9) REs,and thus an ECCE (of EPDCCH) may contain less than 36 REs. In contrast,a CCE of PDCCH always contains thirty six (36) REs.

The space allocated for EPDCCH may be used for PDSCH on discretion ofthe eNB (base station). It is desirable for the UEs to be able to useEPDCCH for receiving paging messages, especially when a UE islink-budget limited. Accordingly, as previously mentioned, the proposalto extend use of the EPDCCH to the common search-space (SS) waspresented in U.S. Provisional patent application Ser. No. 15/076,967.Extending use of the EPDCCH to the common SS makes it possible fortransmitting paging DCIs (with P-RNTI) on EPDCCH. The common SS may alsobe used for system information messages (with SI-RNTI). Therefore, UEsthat are in RRC-Idle mode may monitor the EPDCCH in the common SS.Consequently, the common SS is meant for UEs that are in RR-Idle mode,while UEs in RRC-connected state may be assigned EPDCCH resources forthe UE-specific SS. In general, the EPDCCH resources (RB pairs) forcommon SS and UE-specific SS do not overlap.

EPDCCH may be transmitted in distributed transmissions or localizedtransmissions. The PRB pairs that make up a PRB set for EPDCCH may becontiguous or spread over the transmission bandwidth (as set forth inthe 3GPP standard). The former is likely to be used with localizedtransmissions while the latter is more suited for distributedtransmissions. An EPDCCH includes a specified number‘L’ of ECCEs, whereL denotes the aggregation level. An ECCE includes four EREGS. Forlocalized transmission, the four EREGs of an ECCE lie in the same PRBpair. For distributed transmission the four EREGs of an ECCE may lie indifferent PRB pairs (as also set forth in the 3GPP standard). That is,each control channel may include several ECCEs, and for localizedtransmissions, one ECCE may be contained wholly in one PRB pair, whilefor distributed transmissions, components of the ECCE (i.e. EREGs) maybe contained in different PRBs. It may be assumed that the EPDCCH oncommon SS is chosen to be either transmitted distributed or localized.The localized and distributed transmission cases are further explainedin detail below.

Resource Allocations for Distributed Transmission

FIG. 6 shows a resource allocation diagram illustrating an exemplaryphysical resource block pair when used for EPDCCH for distributedtransmission. For decoding EPDCCH, Cell-Specific Reference Signals (CRS)are not used. Instead Demodulation Reference Signals (DMRS) are definedin each PRB pair carrying EPDCCH. For distributed transmission ofEPDCCH, two transmission ports denoted 107 and 109 are used for DMRSwith alternate REs in EREGs using port 107 and 109 (as set forth in the3GPP standard). The two different types of shaded areas in FIG. 6 (andin subsequent figures as well) are used to denote the differenttransmission ports as indicated by the legend in each figure. Thetransmission ports may correspond to physical antennas. E.g., port 107may be transmitted on a first antenna and port 109 may be transmitted ona second antenna. Implementation dependent beamforming may be used onboth ports independently.

FIG. 6 illustrates a PRB pair when used for EPDCCH (for normal cyclicprefix and on a normal subframe). There are 14 OFDM symbols and 12subcarriers. The PRB pair has 16 DMRS (Demodulation Reference Signal)REs and 144 other REs for a total of 168 REs. The lightly shaded squaresdenote DMRS transmitted on port 109, while the darkly shaded squaresdenote DMRS transmitted on port 107.

FIG. 7 shows a resource allocation diagram illustrating an exemplaryphysical resource block pair when used for EPDCCH for distributedtransmission on UE-specific search space. A PRB pair may contains 16EREGs, labeled 0 to 15. Each specific EREG “i” (where “i” represents anumeric indicator) includes 9 REs labeled “i” for normal cyclic prefixin a normal subframe. E.g., there are nine squares with a “1” in them, 9squares with a “2” in them, etc. The REs used for other purposes (e.g.,PDCCH, CRS) are labeled in EREGs for EPDCCH but not used for EPDCCH. Fordistributed EPDCCH, antenna ports 107 and 109 are used for DMRS. Thealternate REs in an EREG use ports 107 and 109 for transmission.Implementation dependent beamforming may be used on both portsindependently. An example is shown for REs that include EREG ‘1’, withthe darker shading denoting port 107 and the lighter shading denotingport 109 for an RE. This is per 3GPP TS standard for EPDCCH on UEspecific SS for distributed transmission on EPDCCH. Overall, two sets ofports are used for transmission of reference symbols in distributedtransmission.

FIG. 8 shows a resource allocation diagram illustrating an exemplaryphysical resource block pair when used for EPDCCH for distributedtransmission with some resource blocks allocated for common search spaceoverlaid with a UE-specific search space, according to some embodiments.It is proposed that for the common search space the alternate REs of anEREG may be transmitted on ports 109 and 107 (complement of UE specificSS). An example is shown in FIG. 8 for REs comprising EREG ‘1’, with thelight shading denoting port 109 and darker shading denoting port 107 foran RE, in contrast with the port assignments for the same REs shown inFIG. 7. This allows reusing REs similar to a multi-user MIMOenvironment. It provides possible sharing of RBs for EPDCCH on common SSand a UE-specific SS. Thus, some of the RBs allocated for common SS maybe overlaid with a UE-specific SS for some UEs, which allows the network(or eNB or managing base station) more flexibility in allocatingresources for EPDCCH. In one sense, if the common SS and the UE-specificSS share some PRB pairs, the order of transmission may be “reversed”insofar that if in the UE-specific SS the REs are transmitted on port107, on the common SS the REs may be transmitted on port 109. Inpractice, only a few of the PRB pairs from the set of PRB pairs for twoEPDCCH SSs may be shared, which may limit “multi user” interference. Itmay be assumed that the common SS EPDCCH follows distributedtransmission and the shared PRB pairs of the UE-specific SS also followdistributed transmission.

Distinguishing between Common SS and UE-specific SS when some PRB Pairsare Shared

FIG. 9 shows a diagram illustrating how receive antennas may be used forreceiving physical control channel information, according to someembodiments. If the UE is equipped with two receive (RX) antennas (suchas UE 910) then it may decode both transmissions using spatialmultiplexing receiver (normal MIMO). However, if the UE is only equippedwith one antenna (such as UEs 902 and 904), there may be no easy way ofdistinguishing between the two transmissions. Oftentimes one port mightbe stronger than the other port in the UE (e.g. 107 stronger in one UE,109 stronger in another UE, as illustrated in FIG. 9). Some interferencemay be present, but it may be overcome by interference cancellationtechniques, such as forward error correction coding and by the fact thatnot all resources are shared between the common SS and UE-specific SS,i.e. only some PRB pairs may be shared. In other words, per the channelbetween eNB and a UE, an RE from antennas 107 may appear weaker while itmay appear stronger from antennas 109, and vice versa. Accordingly, at aUE, for a given SS, the interference from the other SS may be overcomeby using forward error correction (FEC). It should be noted that an ECCEin a distributed transmission has four EREGs but they are nottransmitted on the same PRB. One EREG might be on one PRB pair, anotherEREG might be on a second PRB pair, etc. Accordingly, some of the EREGsmay be expected to be free of or largely unaffected by interference. Asillustrated by 912, a base station (eNB) may transmit an RE of onesearch-space on antennas 107 and an RE for the other SS on antennas 109,using the same time-frequency resource.

Resource Allocations for Localized Transmission

FIG. 10 shows a resource allocation diagram illustrating an exemplaryphysical resource block pair when used for EPDCCH for localizedtransmission. For localized transmission of EPDCCH, four transmissionports, here denoted as 107, 108, 109, and 110 are used for DMRS. TheDMRS pairs 107, 108 and 109,110 are CDM separated (as set forth in the3GPP standard). FIG. 10 shows a PRB pair with 16 DMRS REs and 144 otherREs for a total of 168 REs. The lightly shaded squares denote DMRStransmitted on port 109, 110, while darkly shaded squares denote DMRStransmitted on port 107, 108. As indicated, for localized transmissionfour ports rather than two ports may be used.

FIG. 11 shows a resource allocation diagram illustrating an exemplaryphysical resource block pair when used for EPDCCH for localizedtransmission on UE-specific search space. For a localized transmissionof a particular EPDCCH with a specified number ‘L’ of ECCEs, the REsthat include the ECCEs are transmitted on one of the four antenna ports.The antenna port is selected pseudo-randomly based on UE identity andthe starting ECCE index of the particular EPDCCH, as set forth in the3GPP standard. An example is shown for an EPDCCH of one ECCE (L=1; EREGs2, 6, 10, 14) transmitted on port 107. The REs of the particular EPDCCHare shown in the darkly shaded squares. Note however that REs used forother purposes (e.g., PDCCH, CRS) are not used for EPDCCH.

FIG. 12 shows a resource allocation diagram illustrating an exemplaryphysical resource block pair when used for EPDCCH for localizedtransmission with some resource blocks allocated for common search spaceoverlaid with a UE-specific search space, according to some embodiments.It is assumed that the common SS EPDCCH follows localized transmissionand the shared PRB pairs of the UE-specific SS also follow localizedtransmission. If on the shared PRB pair, the ECCEs in (or of) aUE-specific SS EPDCCH are being transmitted on port 107, then the sameECCEs may be used for an EPDCCH on common SS using port 109. An exampleis shown in FIG. 12 for an EPDCCH of one ECCE (L=1; EREGs 2, 6, 10, 14)transmitted on port 109. The REs of the particular EPDCCH are shown inthe lightly shaded squares. It should be noted, however that REs usedfor other purposes (e.g., PDCCH, CRS) are not used for EPDCCH.Generally, when using the common SS, the same port cannot be used,instead the port denoted by the light shading is used. Multi-user MIMOmay be used in UE-specific SS. The same resources, e.g. on the portdenoted by the darker shading, are used for one UE, and on the sameresources another EPDCCH may be transmitted using one of the other threeports. Thus, multi-user MIMO may be used on the same resources.

Overlay Reception of EPDCCH

Decoding of the EPDCCH with localized transmission may be performed asfollows. The UEs on common SS may use the port-number as an additionalhypothesis. Alternatively, common SS EPDCCH may always be sent using apredetermined antenna-port. The UE requiring the same antenna port (aspreviously explained) may not be scheduled in that subframe for thatparticular ECCE(s) depending on the aggregation level. The predeterminedantenna port for common SS may be a function of the subframe number andphysical cell ID. The UEs with two RX antennas may preferably use aspatial multiplexing receiver to simultaneously decode transmissionsfrom the port for common SS and the ports from UE-specific ports. Sincethe total number of ports is specified (e.g. four), the decodingcomplexity may increase. Some rules may be used by the network to easethis complexity. For example, if a common EPDCCH is transmitted on ashared PRB on port 107, the NW may not schedule any UE on UE-specific SSthat requires ports 108 or 110. Therefore, in this example the spatialmultiplexing receiver may assume transmissions only on ports 107 and109. In other words, the network (eNB) may ensure that nothing isscheduled on the UE-specific SS if the port numbers clash. Transmissionsmay proceed for different port numbers. In this way, some of the RBsallocated for common SS may be overlaid with a UE-specific SS for someUEs. This allows the eNB more flexibility in allocating resources forEPDCCH. In practice, only a few of the PRB pairs from the set of PRBpairs for two EPDCCH SSs may be shared, limiting “multi user”interference.

EPDCCH—Extended Cyclic Prefix and Other Subframe Types

For extended cyclic prefix, DMRS may be transmitted on ports 107 and108, which share the same REs but are distinguished by CDM (codedivision multiplexing). For distributed transmission on common SS, an REmay be transmitted on the port on which the UE-specific SS is nottransmitting. Similarly for localized transmission, if the UE-specificECCE is being transmitted on port 107, the common SS ECCE may betransmitted on port 108, and vice versa. For special subframes, thenumber of symbols is smaller and hence the number of available REs issmaller. The locations of DMRS are also different. However, the commonSS and UE-specific SS may be overlaid as described above.

Control Channels for MTC

As previously mentioned, 3GPP LTE uses PDCCH as the control channelwhich is transmitted over the whole bandwidth in the first few OFDMsymbols of a subframe. As also mentioned, a subframe generally consistsof 14 OFDM symbols of which one to four symbols can be used for PDCCH.For economy of power consumption and reduced device complexity, Cat-Mdevices are defined to receive and transmit in 1.4 MHz (6 PRBs) portionsof the full LTE bandwidth. (The full bandwidth is typically 5 MHz, 10MHz, 15 MHz, 20 MHz). Thus Cat-M devices cannot use PDCCH. Therefore themechanism of EPDCCH is used to define a control channel called MPDCCH.MPDCCH, as defined, has both the common and user search spaces and thussupports broadcast (SIBs) and paging. MPDCCH is similar to EPDCCH but isrestricted to 6 contiguous PRBs, and uses the concept of “repetitionlevels” to span one or multiple subframes.

For Cat-M devices, two modes are defined, called coverage enhanced modesA and B (CE mode A, and CE mode B). Modes A and B differ in that theyfeature different repetition levels for the PDCCH. Mode B has morerepetition levels for MPDCCH and thus improves the coverage more thanmode A. Two corresponding DCI formats A and B are proposed for modes Aand B, and each contains one UL DCI and one DL DCI format. That is, oneDCI format may be defined for UL and one DCI format may be defined forDL, with the number of DCI bits kept as small as possible.

MPDCCH for Cat-A Devices

The framework defined for Cat-M may be utilized by a different categoryof UEs which may be to a degree link-budget limited but have differentrequirements in terms of throughput and/or real-time traffic such asVoLTE. One such class of devices—described above—is tentatively referredto as Cat-A devices. For a Cat-A device, DL allocations may berestricted to 50 RBs or less (even on a 20 MHZ bandwidth with 100 RBs)and the UL allocations may be restricted to 15 RBs or less. Cat-Adevices in a link-budget-limited scenario may use MPDCCH as thecontrol-channel (a Cat-A device may also use PDCCH and EPDCCH asoptions). For example, when operating on a 20 MHz cell but onlysupporting 10 MHz, PDCCH cannot be used but either EPDCCH or MPDCCH maybe used. Thus, in very poor link conditions, MPDCCH mode may bemimicked. However, the DCIs defined for Cat-M are only suitable for 1.4MHz devices, therefore there is a need to define DCI formats for Cat-Adevices as MTC is limited to 6 RBs.

Since the allocations for Cat-M devices is limited to 6 RBs, theallocation in DCIs is split into two parts. Since Cat-A is limited to 15RBs in UL, similar simplification in specifying the allocation similarto CE mode DCI formats may be allowed. A proposed UL DCI format forCat-A devices may thus include a narrowband index value with a fieldsize defined as “ciel(log2(number of narrowbands)), and a PRB assignmentvalue with a specified field size “n”. The narrowband index isrepresentative of the total BW divided into portions of 15 RBs and thePRB assignment is representative of the PRB location within theconfigured narrowband.

Cat-A devices may be limited to a maximum of 50 RBs in DL. For BW>10MHz, and a narrowband index in DL DCI may select/determine a band of 50RBs. Since the lengths of DCIs for Cat-A may be different than thelengths of DCIs for Cat-M, these may be easily discriminated in thereceiver. Therefore, this definition of DCIs may have no effect on MTCdevices. A proposed DL DCI format for Cat-A devices may thus include anarrowband index value with a field size defined as “ciel(log2(number ofnarrowbands)), and a PRB assignment value with a specified field size“n”. The narrowband index is representative of the total BW divided intoportions of 50 RBs and the PRB assignment is representative of the PRBlocation within the configured narrowband.

In general, the above defines which narrowband is selected on the totalBW, and what the PRB assignment is within the selected narrowband. TheDCI format may be different than the DCI format for Cat-M. If a DCI fora Cat-A device is transmitted, the Cat-M device is not able to decodethat DCI because the length of the DCI is different. This avoidsclashing with other UEs. Hence the DCI length effectively differentiatesbetween Cat-A devices and Cat-M devices.

MPDCCH Overlay

The MPDCCH is similar to EPDCCH but restricted to 6 contiguous PRBs. TheMPDCCH may use localized or distributed transmissions. A PRB pair usedfor MPDCCH may thus be overlaid with an EPDCCH, provided it is assigneda port that is orthogonal (e.g. port 107 or port 108) to the oneassigned to MPDCCH (e.g. port 109 or port 110).

Since localized transmission EPDCCH on UE-specific SS may have up tofour different transmissions, it may complicate the decoding by thereceiver if a PRB-pair is shared between UE-specific SS EPDCCH andcommon SS EPDCCH. Furthermore, for a given aggregation level, a singletransmission port may be used for all ECCEs in/of a particular EPDCCH,and thus the port numbers that clash may limit the network flexibilityin scheduling EPDCCHs. Due to the fact that MTC devices are possiblycoverage limited single-antenna devices, overlaying resources may causeunacceptable interference, and thus is unlikely to be used. In otherwords, some resources may be shared between MPDCCH and EPDCCH, with somePRB pairs—but not all of them—overlaid. However, for localizedtransmissions it may not be as advantageous for MTC devices to shareresources due to interference and the already limited BW associated withMTC devices.

Based at least on the above, wireless cellular communication of a UEaccording to some embodiments may be performed as illustrated in FIG.13. The UE may be identified to a cellular base station as a devicebelonging to a first device category (e.g. Cat-A) for at least purposesof certain default resource allocations (1302). The UE may communicatewith the cellular base station according to parameters that specify howthe UE is expected to communicate with the cellular base station, basedat least in part on the category designation of the UE (1304). Fordownlink communications, the UE may use any physical channel of a groupof physical channels—which may include PDCCH, EPDCCH and MPDCCH—todecode the DCI, with selection of the physical channel based on a set ofcriteria, e.g. QoS and/or link budget requirements associated withvarious operations of the UE (1306).

Embodiments of the present invention may be realized in any of variousforms. For example, in some embodiments, the present invention may berealized as a computer-implemented method, a computer-readable memorymedium, or a computer system. In other embodiments, the presentinvention may be realized using one or more custom-designed hardwaredevices such as ASICs. In other embodiments, the present invention maybe realized using one or more programmable hardware elements such asFPGAs.

In some embodiments, a non-transitory computer-readable memory medium(e.g., a non-transitory memory element) may be configured so that itstores program instructions and/or data, where the program instructions,if executed by a computer system, cause the computer system to perform amethod, e.g., any of a method embodiments described herein, or, anycombination of the method embodiments described herein, or, any subsetof any of the method embodiments described herein, or, any combinationof such subsets.

In some embodiments, a device (e.g., a UE) may be configured to includea processor (or a set of processors) and a memory medium (or memoryelement), where the memory medium stores program instructions, where theprocessor is configured to read and execute the program instructionsfrom the memory medium, where the program instructions are executable toimplement any of the various method embodiments described herein (or,any combination of the method embodiments described herein, or, anysubset of any of the method embodiments described herein, or, anycombination of such subsets). The device may be realized in any ofvarious forms.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

The invention claimed is:
 1. An apparatus comprising: a processingelement configured to cause a wireless communication device to: performcommunications with a cellular base station, wherein the wirelesscommunication device is identified to the cellular base station as adevice that belongs to a first device category; operate according to aplurality of communication parameters that specify how the wirelesscommunication device communicates with the cellular base station, basedat least in part on the first device category; select, based on a set ofcriteria associated with one or more of the plurality of communicationparameters, a physical control channel from among a plurality ofphysical control channels that includes a physical downlink controlchannel (PDCCH), an enhanced PDCCH (EPDCCH), and a Machine TypeCommunications PDCCH (MPDCCH); and decode Downlink Control Information(DCI), using the selected physical control channel.
 2. The apparatus ofclaim 1, wherein the processing element is configured to further causethe wireless communication device to recognize which DCI of a pluralityof DCIs on the MPDCCH to decode based at least on a length of the DCI.3. The apparatus of claim 2, wherein the length of the DCI on the MPDCCHdecoded by the wireless communication device is different from a lengthof other DCIs of the plurality of DCIs on the MPDCCH decoded by otherdevices belonging to a device category other than the first devicecategory.
 4. The apparatus of claim 1, wherein, for distributedtransmissions, at least some resources are shared between the EPDCCH oncommon search space and one or more of the following: the MPDCCH; or theEPDCCH on wireless communication device-specific search space.
 5. Theapparatus of claim 4, wherein the at least some resources are shared byoverlaying one or more but not all physical resource block pairs.
 6. Theapparatus of claim 4, wherein resource elements are transmitted onmultiple respective ports, wherein the processing element is configuredto further cause the wireless communication device to access the atleast some resources through multi-user multiple-input-multiple-output(MIMO) methods.
 7. The apparatus of claim 6, wherein sharing of the atleast some resources is managed by the cellular base station and istransparent to the wireless communication device.
 8. A wirelesscommunication device comprising: radio circuitry configured tofacilitate wireless cellular communications of the wirelesscommunication device; and a processing element communicatively coupledto the radio circuitry and configured to cause the wirelesscommunication device to: communicate with a cellular base station,wherein the wireless communication device is identified to the cellularbase station as a device that belongs to a first device category;operate according to a plurality of communication parameters thatspecify how the wireless communication device communicates with thecellular base station, based at least in part on the first devicecategory; and select, based on a set of criteria associated with one ormore of the plurality of communication parameters, a physical controlchannel from among a plurality of physical control channels thatincludes a physical downlink control channel (PDCCH), an enhanced PDCCH(EPDCCH), and a Machine Type Communications PDCCH (MPDCCH); and decodeDownlink Control Information (DCI), using the selected physical controlchannel.
 9. The wireless communication device of claim 8, wherein theprocessing element is configured to further cause the wirelesscommunication device to recognize which DCI of a plurality of DCIs onthe MPDCCH to decode based at least on a length of the DCI.
 10. Thewireless communication device of claim 9, wherein the length of the DCIon the MPDCCH decoded by the wireless communication device is differentfrom a length of other DCIs of the plurality of DCIs on the MPDCCHdecoded by other devices belonging to a device category other than thefirst device category.
 11. The wireless communication device of claim 8,wherein, for distributed transmissions, at least some resources areshared between the EPDCCH on common search space and one or more of thefollowing: the MPDCCH; or the EPDCCH on wireless communicationdevice-specific search space.
 12. The wireless communication device ofclaim 11, wherein the at least some resources are shared by overlayingone or more but not all physical resource block pairs.
 13. The wirelesscommunication device of claim 11, wherein resource elements aretransmitted on multiple respective ports, wherein the processing elementis configured to further cause the wireless communication device toaccess the at least some resources through multi-usermultiple-input-multiple-output (MIMO) methods.
 14. The wirelesscommunication device of claim 13, wherein sharing of the at least someresources is managed by the cellular base station and is transparent tothe wireless communication device.
 15. A non-transitory memory elementstoring instructions executable by a processing element to cause awireless communication device to: perform wireless communications with acellular base station, wherein the wireless communication device isidentified to the cellular base station as belonging to a first devicecategory; operate according to a plurality of communication parametersthat specify how the wireless communication device performs the wirelesscommunications with the cellular base station, based at least in part onthe first device category; select, based on a set of criteria associatedwith one or more of the plurality of communication parameters, aphysical control channel from among a plurality of physical controlchannels that includes a downlink control channel (PDCCH), an enhancedPDCCH (EPDCCH), and a Machine Type Communications PDCCH (MPDCCH); anddecode Downlink Control Information (DCI), using the selected physicalcontrol channel.
 16. The non-transitory memory element of claim 15,wherein the instructions are executable by the processing element tofurther cause the wireless communication device to recognize which DCIof a plurality of DCIs on the MPDCCH to decode based at least on alength of the DCI; wherein the length of the DCI on the MPDCCH decodedby the wireless communication device is different from a length of otherDCIs of the plurality of DCIs on the MPDCCH decoded by other devicesbelonging to a device category other than the first device category. 17.The non-transitory memory element of claim 15, wherein, for distributedtransmissions, at least some resources are shared between the EPDCCH oncommon search space and one or more of the following: the MPDCCH; or theEPDCCH on wireless communication device-specific search space.
 18. Thenon-transitory memory element of claim 17, wherein the at least someresources are shared by overlaying one or more but not all physicalresource block pairs.
 19. The non-transitory memory element of claim 17,wherein resource elements are transmitted on multiple respective ports,wherein the instructions are executable by the processing element tofurther cause the wireless communication device to access the at leastsome resources through multi-user multiple-input-multiple-output (MIMO)methods.
 20. The non-transitory memory element of claim 19, whereinsharing of the at least some resources is managed by the cellular basestation and is transparent to the wireless communication device.